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Author Topic: Another eBay Nightmare Purchase PM Research Bronze #1 Steam Engine  (Read 362 times)

crazydoug

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If you were  bidding on this engine last week, you should be very happy you did NOT win it!  i already have a very nice PM Research #1 Drilling Engine, but it is a later cast iron version and these early bronze engines are hard to find.  Unfortunately, when it arrived, it did not run.  The piston was binding in the cylinder and the flywheel would not even turn over.  Upon disassembly, I found that the cylinder was gouged and tapered, and the piston was .008 smaller diameter than the cylinder, with Teflon rings.

I had to bore the cylinder out as much as possible without cutting into one of the cylinder head bolt holes, which, by the way, were not drilled in a symmetrical pattern.  I then made a new cast iron piston and used graphite yarn packing for the rings.  After reassembly, I thought at first that the piston was hitting the bottom of the cylinder, but after I verified that it was indeed centered in the cylinder, I then pulled the valve chest apart and found that the valve itself needed to be adjusted.  It was hitting inside the valve chest at one end of the stroke.

Next, I realized that was not quite the problem.   The problem was the valve was not made to specs, and it needed milled down on both ends.  I also noticed the mating surface of the valve was not flat, and again, not machined to specs.  I was able to mill the valve down so that it laid flat and was finally machined to spec.  After some new gaskets, reassembly, and some timing adjustment, it finally runs as it should, on only a couple pounds of air pressure.  I will try it on steam soon.  It should run fine on steam, with all new packing, gaskets, and getting rid of the Teflon rings, which seem to expand greatly under steam. 

So, now it's a keeper, after all!  And, I hope to get some information as to a date of manufacture.  PM Research will be at NAMES, so hopefully they will have the information I am looking for. 




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St Paul Steam

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well Doug...I had my eye on this one , but somehow wasn't watching at the end...I'm glad it ended up in your hands (even though you had a lot of work to make it right) as it would have been sitting on a shelf at shae St. Paul Steam land.
Bruce, St. Paul Indiana, USA
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Stoker

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I'm sure that turned great expectation into savage disappointment, but I'm glad it found the right home in which to be brought back from the terminal illnesses that it had upon arrival at your place Doug!
"Information is not knowledge, Knowledge is not wisdom, Wisdom is not truth, Truth is not beauty, Beauty is not love, Love is not music: Music is THE BEST...   
Wisdom is the domain of the Wis (which is extinct). Beauty is a French phonetic corruption of a short cloth neck ornament currently in resurgence..."
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Jim

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You did a good job on that Doug.

Buying an engine on eBay is really like buying a pig in a poke.
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Cheers.
Jim

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Nick

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May not have been a good purchase at first... but it sure went to the right home!  8)
Nick

classixs

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These bronze versions looks fantastic, and it runs very smoothly...now.

Well done resuscitating this Doug !
Cheers
Jan
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Swift Fox

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I'm glad you were able to sort out the faults Doug, you have a super running engine now!

I must say i really like the ##1 mill engines in bronze, shame they no longer offer that model in that material as i guess it was just too expensive vs cast iron.
Your nose is before your eyes, so trust it first!

komet163b

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Howdy from Brooklyn NY,

  About a year ago I bought a complete PM1 setup - vertical boiler,
water ram, and engine.  It runs but only for a couple minutes on
the steam supplied.  Creating the steam is not a problem and there
ought to be enough for a much longer run.  I used to think it was
too much engine for the boiler, but now I'm sure the engine is a bit
tight.

  The engine seems a bit stiff, so I isolated the crankshaft and that
turns easily.  The connecting rod big-end is also ok.  The valve linkage
is smooth.  The piston rod guides are ok.  That leaves it to something
I can't see and must be in the cylinder.

  So, when turning the flywheel SLOWLY a bit one way then the other
you can feel.....well, it reminds me of rubber catching and letting go
in tiny increments.  This was seconded by an experienced mechanic.
I should mention that the ram had 3 O-rings on it when the plan calls
for 1, so the builder was a 'more is better builder'. 

  I have the plans in hand and am ready to pop the cylinder-head to see
what is going on.  Will I be able to see the ring when the piston is at TDC?
At least rubber is black and TEFLON is white so it is easy to tell them
apart.

  Yours sounded like a nightmare - unfixable by me but it sounds like
you beat it into submission.  What is the least pressure yours needs
to run? 

  I've added a photo or two for good luck,
Wayne
   

Stoker

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That is a fine looking steam plant.

Seems you may be correct, that it is whatever the piston rings turn out to be, expanding and binding as they heat up when running.

I think you'll have to do a bit more than just pull the cylinder head to see the piston rings, as the piston needs to move beyond its TDC position and start out of the cylinder end to address the rings.

Good luck, and I hope it proves to be a simple fix!
"Information is not knowledge, Knowledge is not wisdom, Wisdom is not truth, Truth is not beauty, Beauty is not love, Love is not music: Music is THE BEST...   
Wisdom is the domain of the Wis (which is extinct). Beauty is a French phonetic corruption of a short cloth neck ornament currently in resurgence..."
F. Zappa ... by way of Mary, the girl from the bus.

crazydoug

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That is a fine looking steam plant.

Seems you may be correct, that it is whatever the piston rings turn out to be, expanding and binding as they heat up when running.

I think you'll have to do a bit more than just pull the cylinder head to see the piston rings, as the piston needs to move beyond its TDC position and start out of the cylinder end to address the rings.

Good luck, and I hope it proves to be a simple fix!

You can leave the head on and pull the cylinder. You will probably find the builder either used an aluminum piston, teflon rings or orings that are not a proper fit. The ring grooves have to be cut to a different formula for orings than cast iron or teflon rings. I recommend going to the local plumbing supply house and buying some teflon packing yarn or better yet, graphite packing yarn. Cut a length to fit in the ring groove (one is sufficient-you don't need 3). let the yarn stick out just a little more than being flush with the inside diameter of the cylinder, then force the piston back into the cylinder. Any excess yarn should be shaved off by the sharp front edge of the cylinder, and you will have a perfect fit. This method was used in real steam engines long before rings, but needed changed more often . Since i don't run my model engines24/7 the graphite yarn never wears out and break in time is immediate.
Of course, if your cylinder is scored badly or elliptical in shape, you will have some machining to do.
Show us some pictures when you get it apart.
crazydoug

If you can't find graphite yarn, i can mail you a piece.

crazydoug

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By the way in answer to your last question, my engine now runs on a minimum of @ 2 PSI. A really well machined engine will run on less or even by breath- I have a Tiny Power 104 steam engine that i built that will run on my breath-it is the only one so far of all those i have built.
crazydoug

komet163b

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Two pounds to run - be still my heart! 

  So, it seems to me that the cylinder-head is next.  Removing
the whole cylinder would be a lot of work.  I've rebuilt several
car engines so I feel pretty confident I can get it back together.
Machining is out of the question for me - but there is a vintage
airplane rebuilding shop at Floyd Bennet Field (last I looked)
so if machine work is needed that is where I'm headed.

BTB...Whoever made my setup was compulsive.  Look at the
photo of the bottom of the base!  Machined!

  While TEFLON is the modern way to go, I do like the idea
of the old-fashioned graphite-yarn.  Sounds like the material
used for the crank seals on my old 283ci small-block Chevy
of my 1964 Malibu SS.  Of all my cars it is the one I wish I
had kept on the side.

  I'm retired, so this may take some time.  Four hobbies at
once plus the outside garden.  I'm booked-n-beat.
 
Thanks,
Wayne


Hero

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I have a vertical PM oscillator in bronze that I bought on eBay about 15 years ago, and that remains hopeless to this day. Crank crooked, ports in the wrong place, piston binding--you name it, it's wrong.

Back then, I filled the ports with brazing rod and tried to true the rest, but had no success, so to this day it sits in a box somewhere awaiting another try.

As for eBay itself, I have recently cancelled my account, after being reprimanded for attempting to complete a transaction outside of eBay. What happened was that another eBayer wrote to me suggesting that I phone him and circumvent the auction process. I wrote back saying that such an action was forbidden. eBay's software monitor picked up the correspondence and automatically reprimanded both of us. The humans at eBay refused to rescind my reprimand, despite the clear evidence of my written refusal to violate policy, so I ended a 17-year, 501-transaction association with eBay. I have not once since then re-visited the site and find that I can live quite nicely, thank you, without eBay and its attendant problems.
Bob

txlabman

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Nice save Doug.

You continue to grow your machining skills!